The present invention relates generally to interface devices for allowing humans to interface with computer systems, and more particularly to mechanical computer interface devices that allow the user to provide input to computer systems and provide force feedback to the user.
Computer systems are used extensively in many different industries to implement many applications. Users can interact with a visual environment displayed by a computer on a display device to perform functions on the computer, play a game, experience a simulation or "virtual reality" environment, use a computer aided design (CAD) system, browse the World Wide Web, or otherwise influence events or images depicted on the screen. One visual environment that is particularly common is a graphical user interface (GUI). GUI's present visual images which describe various graphical metaphors of a program or operating system implemented on the computer. Common GUI's include the Windows.RTM. operating system from Microsoft Corporation, the MacOS.RTM. operating system from Apple Computer, Inc., and the X-Windows GUI for Unix operating systems. The user typically moves a user-controlled graphical object, such as a cursor or pointer, across a computer screen and onto other displayed graphical objects or screen regions, and then inputs a command to execute a given selection or operation. Other programs or environments also may provide user-controlled graphical objects such as a cursor and include browsers and other programs displaying graphical "web pages" or other environments offered on the World Wide Web of the Internet, CAD programs, video games, virtual reality simulations, etc. In some graphical computer environments, the user may provide input to control a 3-D "view" of the graphical environment, as in CAD or 3-D virtual reality applications.
The user interaction with and manipulation of the computer environment is achieved using any of a variety of types of human-computer interface devices that are connected to the computer system controlling the displayed environment. A common interface device for GUI's is a mouse or trackball. A mouse is moved by a user in a planar workspace to move a graphical object such as a cursor on the 2-dimensional display screen in a direct mapping between the position of the user manipulandum and the position of the cursor. This is typically known as "position control", where the motion of the graphical object directly correlates to motion of the user manipulandum. One drawback to traditional mice is that functions such as scrolling a document in a window and zooming a view displayed on the screen in or out are typically awkward to perform, since the user must use the cursor to drag a displayed scroll bar or click on displayed zoom controls. These types of functions are often more easily performed by "rate control" devices, i.e. devices that have an indirect or abstract mapping of the user manipulandum to the graphical object, such as pressure-sensitive devices. Scrolling text in a window or zooming to a larger view in a window are better performed as rate control tasks, since the scrolling and zooming are not directly related to the planar position of a mouse. Similarly, the controlled velocity of a simulated vehicle is suitable for a rate control paradigm.
To allow the user easier control of scrolling, zooming, and other like functions when using a mouse, a "scroll wheel" or "mouse wheel" has been developed and has become quite common on computer mice. A mouse wheel is a small finger wheel provided on a convenient place on the mouse, such as between two mouse buttons, which the user may rotate to control a scrolling or zooming function. Most commonly, a portion of the wheel protrudes out of the top surface of the mouse which the user can move his or her finger over. The wheel typically includes a rubber or other frictional surface to allow a user's finger to easily rotate the wheel. In addition, some mice provide a "clicking" wheel that moves between evenly-spaced physical detent positions and provides discrete positions to which the wheel can be moved as well as providing the user with some physical feedback as to how far the wheel has rotated. The wheel is most commonly used to scroll a document in a text window without having to use a scroll bar, or to zoom a window's display in or out without selecting a separate zoom control. The wheel may also be used in other applications, such as a game, drawing program, or simulation.
One problem with existing mouse wheels is that they are quite limited in functionality. The wheel has a single frictional feel to it, and provides the user with very little tactile feedback as to the characteristics of the scrolling or zooming function employed. Even the mouse wheels having physical detents are limited in that the detents are spaced a constant distance apart and have a fixed tactile response, regardless of the scrolling or zooming task being performed or the characteristics of the doucment or view being manipulated. Providing additional physical information concerning the characteristics of the task that the wheel is performing, as well as allowing the wheel to perform a variety of other tasks in a GUI or other environment, would be quite useful to a user.